Performance of a dual-layer scanner for hybrid SPECT/CBCT

Dietze, Martijn M A; Kunnen, Britt; Velden, Sandra van der; Steenbergen, J H L; Koppert, W.J.C.; Viergever, Max A.; Jong, Hugo W. A. M. de

doi:10.1088/1361-6560/ab15f6

Cited by 11 publications

(12 citation statements)

References 19 publications

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“…A specific case that does not require scheduling changes would be the use of adaptive scanning in interventional SPECT. Our group is developing a mobile, compact SPECT scanner that can be used in the intervention room 10‐12 . We envision that this system could be used to perform a SPECT scan after every 99m Tc‐MAA injection in the pretreatment procedure of radioembolization so that the response to every injection is individually monitored.…”

Section: Discussionmentioning

confidence: 99%

“…Our group is developing a mobile, compact SPECT scanner that can be used in the intervention room. [10][11][12] We envision that this system could be used to perform a SPECT scan after every 99m Tc-MAA injection in the pretreatment procedure of radioembolization so that the response to every injection is individually monitored. For this purpose, adaptive scanning would be beneficial in minimizing the total time spent in the intervention room.…”

Section: Discussionmentioning

confidence: 99%

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Adaptive scan duration in SPECT: Evaluation for radioembolization

et al. 2020

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Purpose: It may be challenging to select the optimal scan duration for single-photon emission computed tomography (SPECT) protocols because the activity distribution characteristics can differ in every scan. Using simulations and experiments, we investigated whether the scan duration can be optimized for every scan separately by evaluating the activity distribution during scanning. We refer to this as adaptive scanning. Methods: The feasibility of adaptive scanning was evaluated for the detection of extrahepatic depositions in the pretreatment procedure of radioembolization, in which 99m Tc-labeled macroaggregated albumin ( 99m Tc-MAA) is injected into the liver. We simulated fast 1-min detector rotations and updated the reconstruction with the newly collected counts after every rotation. The scan was terminated when one of the two criteria was met: (a) when the mask difference of the detected extrahepatic deposition between two consecutive rotations was lower than 5%; or (b) when the reconstructed extrahepatic activity was negligible with respect to the total reconstructed activity (<0.075%). The performance of adaptive scanning was evaluated using a digital phantom with various activity distributions, a physical phantom experiment, and simulations based on 129 patient activity distributions. Results: The digital phantom data showed that the scan termination times substantially depended on the activity distribution characteristics. The experimental phantom data showed the feasibility of adaptive scanning with physical scanner measurements and illustrated that fast detector motion was not limiting the adaptive scanning performance. The patient data showed a large spread in the scan terminations times. By adaptive scanning, the mean scan duration of the patient distributions was shortened from 20 min (current clinical protocol) to 4.8 ± 0.2 min. The detection accuracy of extrahepatic depositions was unaffected and the mean difference in the extrahepatic deposition masks (compared with the 20-min scan) was only 7.0 ± 1.0%. Conclusion: Our study suggests that the SPECT scan duration can be personalized by assessing the activity distribution characteristics during scanning for the detection of extrahepatic depositions in the pretreatment procedure of radioembolization. The adaptive scanning approach might also be of benefit for other SPECT protocols, as long as a measure of interest is available for optimization.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Adaptive scan duration in SPECT: Evaluation for radioembolization

et al. 2020

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“…The prototype dual-layer detector system 15,16 is currently being integrated into a custom C-arm. In the present simulation study, it was assumed that the flat panel could be decreased in thickness and attenuation by relocating the detector electronics.…”

Section: Discussionmentioning

confidence: 99%

“…A device that simultaneously measures nuclear and fluoroscopic projections, 15,16 and that is now under construction, could be used to intrinsically correct for respiratory motion. The motion signal can be extracted from the fluoroscopic projections and be used to allocate the nuclear and fluoroscopic projections to motion bins.…”

Section: Introductionmentioning

confidence: 99%

Respiratory motion compensation in interventional liver SPECT using simultaneous fluoroscopic and nuclear imaging

et al. 2019

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Purpose Quantitative accuracy of the single photon emission computed tomography (SPECT) reconstruction of the pretreatment procedure of liver radioembolization is crucial for dosimetry; visual quality is important for detecting doses deposited outside the planned treatment volume. Quantitative accuracy is limited by respiratory motion. Conventional gating eliminates motion by count rejection but increases noise, which degrades the visual reconstruction quality. Motion compensation using all counts can be performed if the motion signal and motion vector field over time are known. The measurement of the motion signal of a patient currently requires a device (such as a respiratory belt) attached to the patient, which complicates the acquisition. The motion vector field is generally extracted from a previously acquired four‐dimensional scan and can differ from the motion in the scan performed during the intervention. The simultaneous acquisition of fluoroscopic and nuclear projections can be used to obtain both the motion vector field and the projections of the corresponding (moving) activity distribution. This eliminates the need for devices attached to the patient and provides an accurate motion vector field for SPECT reconstruction. Our approach to motion compensation would primarily be beneficial for interventional SPECT because the time‐critical setting requires fast scans and no inconvenience of an external apparatus. The purpose of this work is to evaluate the performance of the motion compensation approach for interventional liver SPECT by means of simulations. Methods Nuclear and fluoroscopic projections of a realistic digital human phantom with respiratory motion were generated using fast Monte Carlo simulators. Fluoroscopic projections were sampled at 1–5 Hz. Nuclear data were acquired continuously in list mode. The motion signal was extracted from the fluoroscopic projections by calculating the center‐of‐mass, which was then used to assign each photon to a corresponding motion bin. The fluoroscopic projections were reconstructed per bin and coregistered, resulting in a motion vector field that was used in the SPECT reconstruction. The influence of breathing patterns, fluoroscopic imaging dose, sampling rate, number of bins, and scanning time was studied. In addition, the motion compensation method was compared with conventional gating to evaluate the detectability of spheres with varying uptake ratios. Results The liver motion signal was accurately extracted from the fluoroscopic projections, provided the motion was stable in amplitude and the sampling rate was greater than 2 Hz. The minimum total fluoroscopic dose for the proposed method to function in a 5‐min scan was 10 µGy. Although conventional gating improved the quantitative reconstruction accuracy, substantial background noise was observed in the short scans because of the limited counts available. The proposed method similarly improved the quantitative accuracy, but generated reconstructions with higher visual quality. The proposed method provide...

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“…Work is ongoing on the development of mobile and compact SPECT scanners. [1][2][3] However, the associated costs of a new scanner might raise a threshold for widespread application in clinical practice. It would be beneficial if a method for interventional SPECT scanning is developed which does not require the purchase of an additional scanner.…”

Section: Introductionmentioning

confidence: 99%

Technical Note: Nuclear imaging with an x‐ray flat panel detector: A proof‐of‐concept study

et al. 2020

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Interventional procedures involving radionuclides (e.g., radioembolization) would benefit from single-photon emission computed tomography (SPECT) performed in the intervention room because the activity distribution could be immediately visualized. We believe it might be possible to perform SPECT with the C-arm cone beam computed tomography (CBCT) scanner present in the intervention room by equipping the x-ray flat panel detector with a collimator. The purpose of this study is to demonstrate the approach and to investigate the achievable SPECT reconstruction quality. Methods: A proof-of-concept experiment was performed to evaluate the possibility of nuclear imaging with an x-ray flat panel detector. The experiment was digitally replicated to study the accuracy of the simulations. Three flat panel configurations (with standard hardware and reconstruction methodology, with sophisticated reconstruction methodology, and with expected future hardware) and a conventional gamma camera were evaluated. The Jaszczak and the NEMA IQ phantom (filled with 99m Tc) were simulated and assessed on resolution and contrast-to-noise ratio (CNR). Results: The proof-of-concept experiment demonstrated that nuclear images could be obtained from the flat panel detector. The simulation of the same configuration demonstrated that simulations could accurately predict the flat panel detector response. The CNR of the 37 mm sphere in the NEMA IQ phantom was 22.8 AE 1.2 for the gamma camera reconstructions, while it was 11.3 AE 0.7 for the standard flat panel detector. With sophisticated reconstruction methodology, the CNR improved to 13.5 AE 1.4. The CNR can be expected to advance to 18.1 AE 1.3 for future flat panel detectors. Conclusions: The x-ray flat panel detector of a CBCT scanner might be used to perform nuclear imaging. The SPECT reconstruction quality will be lower than that achieved by a conventional gamma camera. The flat panel detector approach could, however, be useful in providing a cost-effective alternative to the purchase of a mobile SPECT scanner for enabling interventional scanning.

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Performance of a dual-layer scanner for hybrid SPECT/CBCT

Cited by 11 publications

References 19 publications

Adaptive scan duration in SPECT: Evaluation for radioembolization

Adaptive scan duration in SPECT: Evaluation for radioembolization

Respiratory motion compensation in interventional liver SPECT using simultaneous fluoroscopic and nuclear imaging

Technical Note: Nuclear imaging with an x‐ray flat panel detector: A proof‐of‐concept study

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